For me, I use the horizontal distance vs the true distance so I don't have to input another number in my ballistics program (shooter). The horizontal range is the number that is meaningful to your bullet flight anyway.

Using the horizontal distance isn't an accurate method for long range sloped shots. Especially long range shots involving substantial angle. The longer the range and the greater the slope, the greater the error.

You lost me on that one. Horizontal distance IS the corrected distance for slope angle. If you want to do it the hard way go ahead. Either use slope angle in degrees or cosine angle and do the math. I know an ex army sniper who does this. I sit there and wait for him to ge the math done while I already have the scope programmed and ready for a shot. It is a good form of entertainment. Don't get me wrong, if my high dollar gizmo fails I might be screwed......well actually I will just do the math and dial the scope. Cosine indicators are amazingly simple.

For those of use using $800 Leica's or other good RF's, or better yet a G7, we don't have to worry about it any more. The math is done in about .25 seconds. I will continue to input the corrected horizontal distance from my Leica and make my shots.

Oh and for those of you wanting to change out your turrents to the G7 style this is a great way to go. I will be doing this soon. Yardage on top and MOA on the bottom. Crazy fast and simple. Literally, take the horizontal distance, let's say 825 yards, spin the turrent to 8 plus 1 click, shoot. I shot a gunwerks LR1200 with this set up. Loved it.

The reason I provided the link was so you could get unlost, if you felt the need.

If you're calculating elevation dope for sloped shots based solely on the calculated horizontal distance (cosine angle times true sloped distance), then you'll have calculated bad elevation dope. The longer the shot and the greater the slope of the shot, the greater the error.

Perhaps you'll be more inclined to pay attention to the member that started the thread I provide the link to, IF you understand that he makes a portion of his living training long range hunters and shooters. He also used to believe that calculating the horizontal distance was the correct way to determine vertical dope. He wrote this thread to correct himself, and others he had errantly instructed - previously.

I read it and understood it. I have not yet had a shot 4 -5 moa low. At 1000 yards that would be 40-50 inches. I have not shot 45 degrees but I have shot 800 yards at 20 degrees up and was dead on. I will have to get out there and test the higher slope angles and see if it changes things. The ipod program lets you use the ipod to measure angle and lock the number in. The program gives you a result just as Mr Carlock mentions.

Max spread is 4.1 moa. Difference between horizontal and computer is 1.9 MOA. That is if I did the math right. So that would suggest if you simply took the ACI x yards you could be at least 1.9 MOA or 19 inches low vs a computer program. I am not convinced the ACI x drop is accurate yet. That is incredibly steep angle to only pull 75 yards off the entire number. I am thinking your impact would be high.

OK. If I did this all correctly and the slope is now 15 degrees, fairly normal slope......